The present invention relates to an apparatus for judging a bump, which is established on printed circuit boards, etc., whether the bump height is proper or not.
Heretofore, on a printed circuit board and on a semiconductor chip, a bump is formed as an electrical connecting means with other electronic component. It is necessary that a height of the bump be in a predetermined range. For example, when a height of a solder bump formed on a printed circuit board is too low, because an amount of solder, which forms the bump, is too small, electric connection becomes inadequate. On the contrary, when the height of the bump is too high, because the amount of the solder, which forms the bump, is too large, it short-circuits with adjacent bumps when the printed circuit board is connected to electronic circuit elements such as IC or the like.
Moreover, further efficiency improvement is necessary for the judging whether bumps are proper or not, as the number of the bumps exceeds 1000 on a recent large-scale integrated circuit (LSI).
The present invention has been made in order to cope with the above-described demand. An object of the present invention is to provide an apparatus for judging a bump height, capable of efficiently and moreover reliably judging whether a bump height is proper or not.
To achieve the object, the first invention is an apparatus for judging whether a bump height is proper or not includes: an imaging means disposed above a bump as an object to be measured, and configured to capture a surface image of a surface of the bump; a reference object disposed so that an image of the reference object viewed from the imaging means is reflected on the surface of the bump; a judgment means configured to measure, based on image data obtained by the imaging means, a distance between an image position of the image on the surface of the bump and a predetermined position, which is on an edge side of a radial direction of the bump when viewed from the image position, and to judge whether the bump height is proper or not by comparing a value of the distance with a preset reference value.
The second invention is an apparatus for judging whether a bump height is proper or not in the first invention, wherein the predetermined position is an edge position of the bump.
The third invention is an apparatus for judging whether a bump height is proper or not in the first invention, wherein the predetermined position is a position on the surface of the bump of a second reference object, which is disposed so that an image of the second reference object viewed from the imaging means, is reflected on the surface of the bump.
The forth invention is an apparatus for judging whether a bump height is proper or not in the first invention, wherein the position of the image on the surface of the bump is a position in the bump top side of the image and the predetermined position is a position in the bump edge side of the image.
(OPERATION)
In the first invention, the imaging means is disposed above the bump in order to settle multiple bumps in one imaging field. And, the image data of the bump surface obtained by the imaging means contain data, which can calculate a value of a distance between 2 points being located in a bump radial direction. Moreover, the value of the distance has a correlation for the bump height. Therefore, the time for the judging where the bump height is proper or not can be shortened, though the first invention is a simple apparatus.
Especially, it becomes that in case of a bump with a shape in which a height as an edge portion increases rapidly (so usual bump does), the position in the bump edge side of superscription of two points is hard to receive an effect of the bump height in comparison with the position in the bump top side, and becomes constant. Therefore, if position data of the bump edge side are handled as a constant value, the apparatus of this first invention can also reduce image processing data volume. So high speed judging is more possible for this apparatus.
In the second invention, as the position of the bump edge side is fixed in the bump edge, the position data become constant. So this apparatus can realize the high-speed judging with accuracy.
In the third invention, the position of the bump edge side can be set at the position of the desire. Therefore, even if there is a point of an improper surface state in the bump, the measuring point can be set by the avoiding point. So high-precise and stabilized judging is possible for this apparatus.
The forth invention is an apparatus for judging whether a bump height is proper or not of a simple composition which can achieve the action of the third invention in reference object of one.